Vol. 3] Kofoid. — DinoflageUatn — New Species. 309 



but it appears to extend from a collared apical pore to a broadly 

 expanded posterior end near the antapex, and to be somewhat 

 narrower on the epitheea than on the hypotheca. 



Thecal plates as follows : 6 apical, of which 5 are wedge- 

 shaped and one, the furrow plate, almost linear ; 6 precingular ; 

 6 postcingular, and 1 longitudinal ventral furrow plate ; 1 antap- 

 ical with postero-dorsal exposure ; and the ribbon-like girdle plate. 

 Surface marked by a few scattered longitudinal striae and scat- 

 tered pores. Transverse furrow ribbed at regular intervals. 

 Suture lines often marked by 2-5 approximated parallel striae 

 between some of which cross striae appear in places. 



Only the skeleton thus far observed. 



Length, 142/a ; transverse diameter at girdle, 92/i, ; altitude of 

 epitheea, 92/a ; of hypotheca, 78/a ; width of girdle, 5.5. 



Singly in oceanic plankton off San Diego in summer. 



Peridinium crassipes, sp. nov. 



PI. 31, figs. 46, 47. 



A medium-sized species related to P. depressiim, with oblique 

 girdle and short, stout antapicals. 



The body is low and stout, its length being 1.1 transdiameters. 

 It is slightly dorso-ventrally flattened, the greatest dorso-ventral 

 diameter being 0.9 of the transdiameter. It is excavated ventrally 

 and has a reniform girdle section. 



The main axis is deflected antero-dorsally from a perpendic- 

 ular to the plane of the girdle at an angle of 15°. The ventral 

 face of both epitheea and hypotheca is somewhat concave, but the 

 dorsal convex. There is no apical horn and the antapicals are 

 short and stout, the greatest depression of the postmargin being 

 about 0.15-0.2 of the transdiameter. This species is characterized 

 primarily by the form of the end of the antapicals. Instead of 

 terminating distally in a single conical projection, each ends in a 

 blunt semitruncated projection with two or three principal points, 

 one of which is homologous with the tip of the antapical and the 

 other two represent respectively dorsal and ventral angles of the 

 wide (dorso-ventrally) postmargin Avhich forms in a dorso-poste- 

 rior view a sort of an arch with wider posterior and narrow ante- 

 rior opening. The median ventral points are formed by posterior 

 extensions of the lists of the longitudinal furrow. 



